U.S. patent application number 15/791897 was filed with the patent office on 2018-03-01 for polyurethane sealant based on poly(butylene oxide) polyols for glass sealing.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Laura A. Grier, Bindu Krishnan.
Application Number | 20180057721 15/791897 |
Document ID | / |
Family ID | 50687680 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180057721 |
Kind Code |
A1 |
Krishnan; Bindu ; et
al. |
March 1, 2018 |
Polyurethane Sealant Based on Poly(Butylene Oxide) Polyols for
Glass Sealing
Abstract
A polyurethane glass sealant is made by reacting a
poly(1,2-butylene oxide) polymer with a chain extender and a
polyisocyanate. The poly(1,2-butylene oxide) polymer may be used as
a mixture with up to 50% by weight of other polyols, including
castor oil. The sealant is especially useful as a secondary sealant
for an insulated glass unit (IGU).
Inventors: |
Krishnan; Bindu; (Lake
Jackson, TX) ; Grier; Laura A.; (Brazoria,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
50687680 |
Appl. No.: |
15/791897 |
Filed: |
October 24, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14763516 |
Jul 26, 2015 |
9816018 |
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PCT/US2014/031521 |
Mar 21, 2014 |
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15791897 |
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61806051 |
Mar 28, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2419/00 20130101;
C08G 18/4812 20130101; C08G 18/6688 20130101; E06B 3/66342
20130101; E06B 3/6733 20130101; Y02B 80/22 20130101; B32B 2307/102
20130101; C08G 2190/00 20130101; B32B 2038/0076 20130101; B32B 7/12
20130101; B32B 2605/006 20130101; B32B 2037/1253 20130101; C08G
18/4854 20130101; C08G 18/3275 20130101; B32B 17/06 20130101; B32B
37/12 20130101; C08G 18/6674 20130101; B32B 2037/1269 20130101;
C08G 18/36 20130101; C08G 18/6696 20130101; C09J 175/08 20130101;
C03C 27/10 20130101 |
International
Class: |
C09J 175/08 20060101
C09J175/08; B32B 7/12 20060101 B32B007/12; B32B 17/06 20060101
B32B017/06; C03C 27/10 20060101 C03C027/10; C08G 18/32 20060101
C08G018/32; C08G 18/36 20060101 C08G018/36; C08G 18/48 20060101
C08G018/48; C08G 18/66 20060101 C08G018/66; E06B 3/663 20060101
E06B003/663; E06B 3/673 20060101 E06B003/673 |
Claims
1. A process for forming a seal between glass and a substrate,
comprising: a) forming a curable reaction mixture by combining
ingredients including 1) a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500 or a mixture of 50 to
99% by weight of a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500 with 1 to 50% by weight
of at least one other polyol selected from (i) polymers and
copolymers of propylene oxide having an equivalent weight of at
least 300 and (ii) a hydroxyl-containing fat or oil, wherein
component 1) has an average nominal functionality of at least 2.2
hydroxyl groups per molecule; 2) at least one chain extender and 3)
at least one organic polyisocyanate, wherein the isocyanate index
is 70 to 130; b) applying the curable reaction mixture to an
interface between said glass and said substrate and in contact with
both said glass and said substrate; c) curing the curable reaction
mixture to form an elastomeric seal between the glass and the
substrate.
2. A process for producing an edge seal for a multi-pane glass
assembly, wherein the multi-pane glass assembly comprises at least
one pair of substantially parallel glass sheets, the glass sheets
of said pair being separated from each other by one or more spacers
positioned between the pair of glass sheets at or near at least one
edge of the glass sheets; the process comprising a) applying a
curable reaction mixture to said at least one edge of the pair of
glass sheets and into contact with each of the pair of glass sheets
and the spacer(s) separating said pair of glass sheets and b)
curing the curable reaction mixture to form an elastomeric edge
seal between the pair of glass sheets and adherent to the spacer(s)
separating the pair of glass sheets; wherein the curable reaction
mixture contains 1) a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500 or a mixture of 50 to
99% by weight of a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500 with 1 to 50% by weight
of at least one other polyol selected from (i) polymers and
copolymers of propylene oxide having a hydroxyl equivalent weight
of at least 300 and (ii) a hydroxyl-containing fat or oil, wherein
component 1) has an average nominal functionality of at least 2.2
hydroxyl groups per molecule; 2) at least one chain extender and 3)
at least one organic polyisocyanate, and wherein the isocyanate
index is 70 to 130.
3. The process of claim 2, wherein the poly(1,2-butylene oxide)
polyol preferably has a nominal functionality of 2 to 2.5 and an
equivalent weight per hydroxyl group of 800 to 1500.
4. The process of claim 3, wherein the poly(1,2-butylene oxide) has
an average nominal hydroxyl functionality of at least 2.2 and is
the only polyol having a hydroxyl equivalent weight of 200 or more
in the reaction mixture.
5. (canceled)
6. The process of claim 2 wherein component 1) is a mixture of 70
to 95% by weight of the poly(1,2-butylene oxide) polymer and 5 to
30% by weight of castor oil.
7. The process of claim 6 wherein component 1) is mixture of 85 to
95% by weight of the poly(1,2-butylene oxide) polymer and 5 to 15%
by weight of castor oil.
8. (canceled)
9. The process of claim 7 wherein the chain extender is 1,4-butane
diol or 1,3-propane diol.
10. The process of claim 9, wherein the reaction mixture is devoid
of a plasticizer.
11. The process of claim 9, wherein the reaction mixture contains
10 to 13% by weight of a plasticizer, based on the combined weight
of the plasticizer and all reactive materials provided to the
reaction mixture.
12-24. (canceled)
Description
[0001] This invention relates to a polyurethane sealant for glass
sealing, to a method of sealing glass surfaces, to a method for
making insulated glass units and to insulated glass units sealed
with a polyurethane sealant.
[0002] Sealants are often applied to glass windows to bond the
glass to a frame or other substrate and prevent gas and water
leakage around the edges. An example of this is automotive
windshields. In addition, many building glazing applications rely
on a sealant to bond the glass to the frame structure. The general
requirements for these materials are that they be elastomeric and
that they bond well to glass and other materials. In addition, they
need to form good barriers against the penetration of gases and
liquids. To accomplish this, the sealant materials need to prevent
leakage at the interface between the sealant and the substrates, as
well as through the sealant material itself.
[0003] A glazing application of commercial significance is
insulating glass units (IGUs). IGUs generally comprise two or more
parallel glass panes held a small distance apart by a spacer. The
space enclosed between the panes typically holds a vacuum or is
filled with air or an inert gas such as argon, helium or xenon. The
vacuum or trapped inert gas contributes much of the thermal
insulation properties of these IGUs. Sealants hold the unit
together and provide a barrier to the passage of gas into and out
of the enclosed space between the panes. This is important to
maintain the thermal insulation properties of the units. In
addition, the sealants prevent water from permeating into the unit.
This helps to prevent fogging.
[0004] IGUs typically make use of two different sealant materials.
A "primary" sealant is used to seal the glass panes directly to a
spacer, which as its name implies defines the spacing between
adjacent glass panes and therefore the thickness of the enclosed
vacuum or gas space. The material of choice as the primary sealant
is polyisobutylene, which is an excellent barrier to both moisture
and gasses. However, polyisobutylene does not provide the
mechanical properties and adhesive strength that are needed.
Therefore, it is typical to manufacture the IGU using a secondary
sealant. This secondary sealant provides the necessary adhesion and
mechanical strength, but also is important in preventing the
passage of moisture and gas into and out of the unit, especially if
the primary sealant becomes damaged or degraded over time.
[0005] The highest-performing polyurethane secondary sealant
currently used in IGU is based on a polybutadiene polyol. These
polyurethanes have excellent moisture vapor permeation rates but
suffer from inadequate UV stability. Because of the poor UV
stability, these polyurethane sealants degrade over time, and the
life of the IGU is shortened. These polyurethanes are also
susceptible to hydrolytic instability.
[0006] Other polyurethane secondary sealants have performed even
less well. Those based on polymers of propylene oxide suffer from
high permeabilities to both moisture vapor and gases. They also
show poor UV stability and sometimes inadequate hydrolytic
stability, and IGUs containing them have short lifetimes.
[0007] Low water permeability often does not correlate to low gas
permeability in substantially non-cellular polymers. That is
because low water permeability is favored by a high level of
hydrophobicity in the sealant polymer, and increasing
hydrophobicity tends to favor permeation by atmospheric gases and
non-polar gases such as argon that is commonly used to fill the
space between the glass panes of an IGU. Therefore, measures that
tend to decrease water permeability often are seen to have an
adverse impact on gas permeability, and vice versa.
[0008] Still another drawback of the polyurethanes is that large
quantities of a plasticizer compound often must be included in the
formulation for processing reasons. The polyurethane is typically
made by mixing a polyol component with a polyisocyanate compound.
The significant differences in the viscosities between these
components can lead to difficulties in mixing; thereby requiring
longer mixing times. Due to the reactive nature of the components
used, there are processing drawbacks related to viscosity increase
and exotherm. The plasticizer is included to reduce the viscosity
of the polyol component to facilitate mixing, to ameliorate the
viscosity increase during early stages of cure and to reduce the
exotherm by acting as a heat sink. For these reasons, the
plasticizer is widely understood to be necessary to process the
polyurethane system with the equipment used in the industry. Over
time, this plasticizer can leach into the space between the glass
panes and cause fogging. This potential for fogging can be
ameliorated by reducing the plasticizer level or eliminating it
completely.
[0009] Therefore, it would be desirable to provide a thermosetting,
elastomeric sealant for glass installations, which sealant has good
processing characteristics, exhibits good adhesion to glass,
provides the needed barrier to gasses and liquids (including
atmospheric moisture) and has the necessary physical properties, UV
stability and hydrolytic stability.
[0010] This invention is in one aspect a process for forming a seal
between glass and a substrate, comprising:
[0011] a) forming a curable reaction mixture by combining
ingredients including 1) a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500, or a mixture of 50 to
99% by weight of a poly(1,2-butylene oxide) polyol having a
hydroxyl equivalent weight of at least 500 with 1 to 50% by weight
of at least one other polyol selected from (i) polymers and
copolymers of propylene oxide having an equivalent weight of at
least 300 and (ii) a hydroxyl-containing fat or oil, wherein
component 1) has an average nominal functionality of at least 2.2
hydroxyl groups per molecule; 2) at least one chain extender and 3)
at least one organic polyisocyanate, wherein the isocyanate index
is 70 to 130;
[0012] b) applying the curable reaction mixture to an interface
between said glass and said substrate and in contact with both said
glass and said substrate;
[0013] c) curing the curable reaction mixture to form an
elastomeric seal between the glass and the substrate.
[0014] In specific embodiments, the invention is a process for
producing an edge seal for a multi-pane glass assembly, wherein the
multi-pane glass assembly comprises at least one pair of
substantially parallel glass sheets, the glass sheets of said pair
being separated from each other by one or more spacers positioned
between the pair of glass sheets and at or near at least one edge
of the glass sheets; the process comprising
[0015] a) applying a curable reaction mixture to said at least one
edge of the pair of glass sheets and into contact with each of the
pair of glass sheets and the spacer(s) separating said pair of
glass sheets and
[0016] b) curing the curable reaction mixture to form an
elastomeric edge seal between the pair of glass sheets and adherent
to the spacer(s) separating the pair of glass sheets; wherein the
curable reaction mixture contains 1) a poly(1,2-butylene oxide)
polyol having a hydroxyl equivalent weight of at least 500, or a
mixture of 50 to 99% by weight of a poly(1,2-butylene oxide) polyol
having a hydroxyl equivalent weight of at least 500 with 1 to 50%
by weight of at least one other polyol selected from (i) polymers
and copolymers of propylene oxide having a hydroxyl equivalent
weight of at least 300 and (ii) a hydroxyl-containing fat or oil,
wherein component 1) has an average nominal functionality of at
least 2.2 hydroxyl groups per molecule; 2) at least one chain
extender and 3) at least one organic polyisocyanate, and wherein
the isocyanate index is 70 to 130.
[0017] The invention is also a multi-pane glass assembly comprising
at least one pair of substantially parallel glass sheets, the glass
sheets of said pair being separated from each other by one or more
spacers positioned between the pair of glass sheets at or near at
least one edge of the glass sheets, and an elastomeric edge seal
bonded to said edge of the glass sheets and the spacer(s), wherein
the elastomeric edge seal is a polymer formed by curing a curable
reaction mixture formed by combining ingredients including 1) a
poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight
of at least 500, or a mixture of 50 to 99% by weight of a
poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight
of at least 500 with 1 to 50% by weight of at least one other
polyol selected from (i) polymers and copolymers of propylene oxide
having a hydroxyl equivalent weight of at least 300 and (ii) a
hydroxyl-containing fat or oil, wherein component 1) has an average
nominal functionality of at least 2.2 hydroxyl groups per molecule;
2) at least one chain extender and 3) at least one organic
polyisocyanate, wherein the isocyanate index is 70 to 130.
[0018] This invention provides a readily-processable,
thermosetting, elastomeric sealant for glass installations. The
sealant composition does not require the presence of thiram or
manganese dioxide, which preferably are absent from the
composition. The cured sealant forms a strong elastomeric seal
between glass and a substrate material, with good adhesion and low
permeability to gases and liquids.
[0019] The FIGURE is a side view of a multipane glass assembly
sealed with an elastomeric seal, in accordance with the
invention.
[0020] In this invention, a seal is formed between glass and a
substrate. By "glass", it is meant any inorganic amorphous material
having a glass transition temperature of at least 100.degree. C. It
preferably is transparent to visible light. A preferred type of
glass is a silica glass, by which is meant a glass containing 50%
or more by weight silica. Among the silica glasses are fused silica
glass, soda-lime-silica glass, sodium borosilicate glass, lead
oxide glass, aluminosilicate glass and the like. Another preferred
type of glass is so-called "oxide glass", which contains alumina
and a minor amount of germanium oxide.
[0021] The glass may have one or more coatings on either or both of
its main surfaces. Examples of such coatings include reflective
coatings of various types, such as IR, UV or visible light
reflective surfaces, IR absorbers, UV absorbers, tints or other
coloring layers, and the like.
[0022] The glass may have a multi-layer construction. For example,
the glass may consist of two or more glass layers bonded by one or
more intermediate layers of an adhesive polymer.
[0023] The substrate can be any solid material, including, for
example, a metal, a ceramic, another glass, an organic polymer, a
lignocellulosic material such as wood, paper, cotton and the like
or another biological or natural material. An organic polymer may
be, for example, a synthetic or biological-origin polymer, and may
be a thermoplastic or a thermoset.
[0024] In specific embodiments, the glass forms a window for a
vehicle, building or other construction and the substrate is a
frame element to which the window is affixed. The frame element may
be a vehicle frame structure (or a part thereof). The frame element
may be a window sash, door stile or other structural support to
which the window is affixed.
[0025] In other specific embodiments, the substrate is a spacer for
a multi-pane glass assembly such as an insulating glass unit (IGU).
Such a multi-pane assembly comprises at least one pair of
substantially parallel glass sheets. The glass sheets are separated
from each other by one or more peripheral spacers positioned
between the glass sheets at or near at least one edge. A multi-pane
assembly may contain any larger number of substantially parallel
glass sheets, with each adjacent pair being separated by a
peripheral spacer.
[0026] A representation of a multi-pane assembly is shown in the
FIGURE. In the FIGURE, substantially parallel glass panes 1 are
separated by spacer 2 near edge 11, defining space 4 between the
two glass panes 1. As is typical, spacer 2 is recessed slightly
from edge 11, leaving a cavity 8 that is defined by the interior
faces 10 of each of panes 1 and the exterior surface 9 of spacer 2.
Spacer 2 typically is positioned along the substantial length of
edge 11 of glass panes 1, and more typically spacers such as spacer
2 will be positioned about the entire periphery of glass panes 1.
Sealant 5 of this invention is bonded to said edge 11 of the glass
sheets 1 and to spacer 2, forming a seal between each of glass
panes 1 and spacer 2, and between glass panes 1. As shown, sealant
5 occupies cavity 8 formed defined by the interior faces 10 of each
of panes 1 and the exterior surface 9 of spacer 2.
[0027] In the particular embodiment shown in the FIGURE, spacer 2
is hollow, and is filled with optional desiccant 6. Desiccant 6
often is provided to absorb moisture from the gas contained within
space 4. Space 4 is typically filled with a gas such as air,
nitrogen, helium argon, xenon and the like.
[0028] Also shown in the FIGURE are primary sealants 3, which are
optional but are often included in insulating glass units. Primary
sealants 3 are closest to the air gap between glass sheets 2 and
are generally present to keep moisture vapor and gasses from moving
in and out of space 4. Primary sealant 3 is preferably
polyisobutylene, but may be another polymer having barrier
properties.
[0029] Sealant 5 is a reaction product of a curable reaction
mixture formed by combining at least the following ingredients:
[0030] 1) a poly(1,2-butylene oxide) polyol having a hydroxyl
equivalent weight of at least 500 or a mixture of 50 to 99% by
weight of a poly(1,2-butylene oxide) polyol having a hydroxyl
equivalent weight of at least 500 with 1 to 50% by weight of at
least one other polyol selected from (i) polymers and copolymers of
propylene oxide having a hydroxyl equivalent weight of at least 300
and (ii) a hydroxyl-containing fat or oil, wherein component 1) has
an average nominal functionality of at least 2.2 hydroxyl groups
per molecule; 2) at least one chain extender and 3) at least one
polyisocyanate, and wherein the isocyanate index is 70 to 130.
[0031] The poly(1,2-butylene oxide) polyol is a homopolymer of
1,2-butylene oxide, or a copolymer thereof with up to 25%,
preferably up to 10% and more preferably up to 5%, based on the
combined weight of all monomers, of a copolymerizable alkylene
oxide such as, for example, ethylene oxide, 1,2-propylene oxide,
2,3-butylene oxide, tetrahydrofuran, 1,2-hexane oxide, and the
like. Poly(1,2-butylene oxide) homopolymers are preferred. The
poly(1,2-butylene oxide) polyol can be prepared in known fashion by
polymerizing 1,2-butylene oxide (alone or together with one or more
comonomers as described) in the presence of an initiator compound.
The polymerization is generally catalyzed, using catalysts such as
alkali metal hydroxide, double metal cyanide catalysts and the
like.
[0032] The initiator compound(s) used in the polymerization
contains on average, at least 1.8 groups that can be alkoxylated.
The nominal functionality of the poly(1,2-butylene oxide) polyol is
equal to the number of alkoxylatable sites on the initiator
compound or, if a mixture of initiator compounds is used, the
average number of alkoxylatable sites per molecule in the mixture.
Preferred initiator compounds contain two or more hydroxyl groups,
although compounds containing amine hydrogens are also useful. The
initiator compound preferably has an equivalent weight per
alkoxylatable site of 15 to 150 and more preferably 30 to 75.
Examples of suitable initiator compounds include ethylene glycol,
diethylene glycol, triethylene glycol, 1,2-propane diol,
dipropylene glycol, tripropylene glycol, 1,4-butane diol,
cyclohexane dimethanol, glycerin, trimethylolethane,
trimethylolpropane, erythritol, pentaerythritol, ethylene diamine,
propylene diamine, aniline, toluene diamine, and the like.
[0033] The poly(1,2-butylene oxide) polyol preferably has a nominal
functionality of 2 to 3, more preferably 2 to 2.5, and an
equivalent weight per hydroxyl group of 500 to 3000, especially 800
to 2500 and most preferably 800 to 1500.
[0034] The poly(1,2-butylene oxide) polyol may be the only high
equivalent weight (i.e., 200 g/equivalent or more) polyol in the
reaction mixture, if it has a nominal functionality of at least
2.2. If the poly(1,2-butylene oxide) polyol has a nominal
functionality below 2.2, it is necessary to provide a second polyol
to increase the average nominal functionality to at least 2.2. Such
a second polyol may also be present even if the nominal
functionality of the poly(1,2-butylene oxide) polyol is 2.2 or
greater.
[0035] In some embodiments, the second polyol is a polymer or
copolymer of propylene oxide that has a hydroxyl equivalent weight
of at least 300. The propylene oxide may be 1,3-propylene oxide,
but more typically is 1,2-propylene oxide. If a copolymer, the
comonomer is another copolymerizable alkylene oxide such as, for
example, ethylene oxide, 2,3-butylene oxide, tetrahydrofuran,
1,2-hexane oxide, and the like. A copolymer may contain 75% or more
by weight, preferably 85% or more polymerized propylene oxide,
based on the total weight of polymerized alkylene oxides. A
copolymer preferably contains no more than 15%, especially no more
than 5% by weight polymerized ethylene oxide. The polymer or
copolymer of propylene oxide should have a nominal functionality of
at least 2.0. The nominal functionality preferably is 2.5 to 6,
more preferably 2.5 to 4 or 2.5 to 3. The hydroxyl equivalent
weight of the polymer or copolymer of propylene oxide is at least
300, preferably at least 500, more preferably 500 to 3000, in some
embodiments 800 to 2500 and in particular embodiments from 800 to
1500.
[0036] The polymer or copolymer of propylene oxide can be made in
the same general manner as described with respect to the
1,2-butylene oxide polymer, except for the selection of monomers.
Suitable initiator compounds to produce the polymer or copolymer of
propylene oxide include those described above with respect to the
1,2-butylene oxide polymer.
[0037] In other embodiments, the second polyol is a
hydroxyl-containing fat or oil. The hydroxyl-containing fat or oil
should contain an average of at least two, preferably at least 2.2
hydroxyl groups per molecule. Suitable such oils include
naturally-occurring plant oils such as castor oil and lesquerella
oil. Castor oil is a preferred hydroxyl-containing oil.
[0038] Mixtures of two or more of the foregoing second polyols can
be present.
[0039] When a mixture of polyols is used, the poly(1,2-butylene
oxide) constitutes 50 to 99% by weight of the mixture, and the
second polyol(s) constitutes 1 to 50% thereof. The
poly(1,2-butylene oxide) preferably constitutes 70 to 99% by weight
of the mixture, and more preferably 70 to 90% by weight of the
mixture, with the second polyol(s) correspondingly constituting the
remainder of the weight of the mixture.
[0040] Component 1) has an average nominal hydroxyl functionality
of at least 2.2, and preferably at least 2.3. Its average nominal
hydroxyl functionality may be as high as six, but preferably is up
to 4 and more preferably up to 3. The average hydroxyl equivalent
weight of component 1) may be from about 500 to 3000, and is more
preferably 500 to 1500 and still more preferably from 600 to
1200.
[0041] Especially preferred as Component 1) is a mixture of 70 to
95% by weight of a poly(1,2-butylene oxide) polymer as described
before and 5 to 30% by weight of castor oil. Such especially
preferred mixtures may contain 85 to 95% by weight of the
poly(1,2-butylene oxide) and 5 to 15% by weight of castor oil. In
these especially preferred embodiments, the poly(1,2-butylene
oxide) polyol preferably has a nominal functionality of 2 to 3,
more preferably 2 to 2.5, and an equivalent weight per hydroxyl
group of 500 to 3000, especially 800 to 2500 and most preferably
800 to 1500.
[0042] Component 2) is a chain extender, by which is meant a
compound having exactly two isocyanate-reactive groups and a weight
per isocyanate-reactive group of up to 300, preferably 30 to 150,
and more preferably 30 to 75. The isocyanate-reactive groups may
be, for example, hydroxyl, primary amino or secondary amino groups.
Hydroxyl groups are generally preferred. Examples of
hydroxyl-containing chain extenders are ethylene glycol,
1,2-propane diol, 1,3-propane diol, 1,4-butane diol,
2,2,4-trimethylpentane-1,3-diol, 2-ethylhexane diol,
N,N-bis(2-hydroxylpropyl)aniline, diethylene glycol, triethylene
glycol, dipropylene glycol, tripropylene glycol,
cyclomethanedimethanol, and the like. Among these, the linear,
acyclic, hydroxyl chain extenders are generally preferred, and
.alpha.,.omega.-alkylene glycols and .alpha.,.omega.-polyalkylene
glycols such as ethylene glycol, 1,4-butane diol, 1,3-propane diol,
diethylene glycol, triethylene glycol and the like are especially
preferred.
[0043] The organic polyisocyanate advantageously contains an
average of at least 2.0 isocyanate groups per molecule. A preferred
isocyanate functionality is from about 2.0 to about 3.0 or from
about 2.0 to about 2.5 isocyanate groups per molecule. The
polyisocyanate advantageously has an isocyanate equivalent weight
of 75 to 200. This is preferably from 80 to 170.
[0044] Suitable polyisocyanates include aromatic, aliphatic and
cycloaliphatic polyisocyanates. Exemplary polyisocyanates include,
for example, m-phenylene diisocyanate, 2,4- and/or 2,6-toluene
diisocyanate (TDI), the various isomers of
diphenylmethanediisocyanate (MDI), hexamethylene-1,6-diisocyanate,
tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate,
hexahydrotoluene diisocyanate, hydrogenated MDI (H.sub.12 MDI),
naphthylene-1,5-diisocyanate, methoxyphenyl-2,4-diisocyanate,
4,4'-biphenylene diisocyanate, 3,3'-dimethyoxy-4,4'-biphenyl
diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate,
4,4',4''-triphenylmethane diisocyanate, polymethylene
polyphenylisocyanates, hydrogenated polymethylene polyphenyl
polyisocyanates, toluene-2,4,6-triisocyanate and
4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate. Any of the
foregoing polyisocyanates may be modified to include urea,
isocyanurate, uretidinedione, allophonate, biuret, carbodiimide,
urethane or other linkages.
[0045] Among the preferred polyisocyanates are MDI, "liquid MDI"
products in which MDI is modified to contain urea, uretonimine,
allophonate, biuret, carbodiimide and/or urethane linkages to
produce a material having a melting temperature below 20.degree. C.
and an isocyanate equivalent weight of 135 to 170, and the
so-called polymeric MDI products, which are a mixture of
polymethylene polyphenylene polyisocyanates in monomeric MDI.
[0046] The polyisocyanate is used in an amount sufficient to
provide an isocyanate index of 70 to 130. Isocyanate index is
calculated as the number of reactive isocyanate groups provided to
the reaction mixture divided by the number of isocyanate-reactive
groups provided to the reactive mixture, and multiplying by 100. A
preferred isocyanate index is 90 to 125 and a more preferred
isocyanate index is 95 to 115.
[0047] In addition, the amounts of polyisocyanate and chain
extender (and any crosslinkers as may be present) are chosen
together such that the polyurethane has a hard segment content of
10 to 50%, preferably 15 to 35% and more preferably 18 to 30% by
weight. Hard segment content is calculated by dividing the combined
weight of polyisocyanate(s), chain extender(s) and crosslinker(s)
(if any) by the total weight of all polyisocyanate(s) and
isocyanate-reactive materials (other than reactive catalysts, if
any) provided to the reaction mixture.
[0048] The curable reaction mixture may contain other ingredients
in addition to those already described. Among these are, for
example, catalysts, plasticizers, crosslinkers, UV stabilizers,
biocides, preservatives, adhesion promoters, colorants, fillers,
desiccants and water scavengers, and the like.
[0049] Examples of catalysts include tertiary amines, tin
carboxylates; organotin compounds; tertiary phosphines; various
metal chelates; metal salts of strong acids, such as ferric
chloride, stannic chloride, stannous chloride, antimony
trichloride, bismuth nitrate and bismuth chloride, and the like.
Tertiary amine and tin catalysts are generally preferred.
[0050] Representative tertiary amine catalysts include
trimethylamine, triethylamine, N-methylmorpholine,
N-ethylmorpholine, N,N-dimethylbenzylamine,
N,N-dimethylethanolamine, N,N,N',N'-tetramethyl-1,4-butanediamine,
N,N-dimethylpiperazine, 1,4-diazobicyclo-2,2,2-octane,
bis(dimethylaminoethyl)ether, bis(2-dimethylaminoethyl) ether,
morpholine, 4,4'-(oxydi-2,1-ethanediyl)bis, triethylenediamine,
pentamethyl diethylene triamine, dimethyl cyclohexyl amine, N-cetyl
N,N-dimethyl amine, N-coco-morpholine, N,N-dimethyl aminomethyl
N-methyl ethanol amine, N,N,N'-trimethyl-N'-hydroxyethyl
bis(aminoethyl) ether,
N,N-bis(3-dimethylaminopropyl)N-isopropanolamine, (N,N-dimethyl)
amino-ethoxy ethanol, N,N, N',N'-tetramethyl hexane diamine,
1,8-diazabicyclo-5,4,0-undecene-7, N,N-dimorpholinodiethyl ether,
N-methyl imidazole, dimethyl aminopropyl dipropanolamine,
bis(dimethylaminopropyl)amino-2-propanol, tetramethylamino bis
(propylamine), (dimethyl(aminoethoxyethyl))((dimethyl
amine)ethyl)ether, tris(dimethylamino propyl) amine, dicyclohexyl
methyl amine, bis(N,N-dimethyl-3-aminopropyl) amine, 1,2-ethylene
piperidine and methyl-hydroxyethyl piperazine.
[0051] Examples of useful tin-containing catalysts include stannous
octoate, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin
dimercaptide, dialkyl tin dialkylmercapto acids, dibutyl tin oxide,
dimethyl tin dimercaptide, dimethyl tin diisooctylmercaptoacetate,
and the like.
[0052] The catalysts are typically used in small amounts, such as
0.0015 to 5, preferably from 0.01 to 1 part by weight per 100 parts
by weight of polyol(s) plus polyisocyanate(s). Tin-containing
catalysts are typically used in amounts towards the low end of
these ranges.
[0053] A plasticizer may be present. If present, the plasticizer
preferably is mixed with the poly(1,2-butylene oxide) polymer to
reduce its viscosity and so facilitate mixing with the
polyisocyanate, which typically has a much lower viscosity.
Examples of suitable plasticizers include liquid (at 25.degree. C.)
esters of monocarboxylic acids and diesters of dicarboxylic acids
having molecular weights of up to about 300. Among these are, for
example, dialkyl phthalate esters, dialkyl terephthalate esters,
trialkyl trimellitates, dialkyl adipate esters, dialkyl maleate
esters, dialkyl sebacate esters, alkanolic acid diesters of
alkylene glycols, alkanoic acid diesters of polyalkylene glycols,
and the like. A preferred plasticizer is trimethylpentyl
diisobutyrate.
[0054] The amount of plasticizer, if used, may range from 1 to 50%
of the combined weight of the plasticizer and all reactive
materials (isocyanates and isocyanate reactive materials) provided
to the reaction mixture. An advantage of the invention is that
often only small amounts of plasticizer are needed. Therefore, a
preferred amount is from 1 to 20%, in some embodiments 5 to 15%,
and in other embodiments 10 to 13% by weight, on the same basis as
before. The use of a plasticizer tends to reduce tensile strength
while increasing elongation and increasing sag. Since excessive sag
can be a drawback, the ability to use small amounts of plasticizer
(if any at all) can be a significant advantage of this invention.
In addition, smaller amounts of plasticizer in the sealant reduce
the risk and severity of fogging due to the leaching of the
plasticizer.
[0055] Crosslinkers are for purposes of this invention compounds
having at least three isocyanate-reactive groups per molecule and
an equivalent weight per isocyanate-reactive group of less than
200, preferably 30 to 150. Examples of crosslinkers include
glycerin, trimethylolpropane, trimethylolethane, pentaerythritol,
erythritol, sorbitol, and alkoxylates of any of the foregoing
having an equivalent weight of up to 300. If used at all,
crosslinkers are generally present in small quantities, such as up
to 5% of the weight of the curable reaction mixture.
[0056] Fillers can be present to provide desired rheological
properties and reduce cost. Examples of fillers include inorganic
particulate materials such as talc, titanium dioxide, calcium
carbonate, mica, wollastonite, fly ash and the like; metal
particles; carbon black; graphite; high melting organic polymers,
and the like. The particle size of these fillers (as determined
using screening methods) may be up to 50 microns, preferably 0.2 to
30 microns. Fillers may constitute up to 90% by weight of the
curable reaction mixture, preferably 25 to 80% by weight.
[0057] A seal is formed in accordance with the invention by forming
a curable reaction mixture, applying it to an interface between and
in contact with said glass and said substrate and then curing the
curable reaction mixture to form an elastomeric seal between the
glass and the substrate.
[0058] The reaction mixture is formed by mixing the foregoing
necessary and optional (if any) components. It is generally
preferred to formulate the starting ingredients into two
components. The first component includes the isocyanate-reactive
components, including component 1), the chain extender (component
2) and any crosslinker. The second component includes the
polyisocyanate compound(s). The catalyst(s) can be formulated into
either or both of these components, but preferably are formulated
into the first component. The plasticizer if any is preferably
incorporated into the first component.
[0059] Mixing and application can be done in any convenient manner.
In the preferred case in which the ingredients are formulated into
two components, the components are simply combined at ambient
temperature or any desirable elevated temperature, deposited onto
the interface between glass and substrate, and allowed to react.
The mixing of the components can be done in any convenient way,
depending on the particular application and available equipment.
Mixing of the components can be done batchwise, mixing them by hand
or by using various kinds of batch mixing devices, followed by
application by brushing, pouring, applying a bead and/or in other
suitable manner. The two components can be packaged into separate
cartridges and simultaneously dispensed through a static mixing
device to mix and apply them, typically as a bead, onto the
interface.
[0060] Spraying methods are also useful. In a spraying method, the
individual ingredients or formulated components are brought under
pressure to a mixhead, where they are combined and dispensed under
pressure to the interface between glass and substrate.
[0061] Other continuous metering and dispensing systems also are
useful to mix and dispense the reaction mixture and apply it to the
interface between glass and substrate.
[0062] Curing in many cases proceeds spontaneously at room
temperature (about 20.degree. C.), and in such cases can be
effected without application of heat. The curing reaction is
generally exothermic, and a corresponding temperature rise may
occur.
[0063] A faster and/or more complete cure often is seen at higher
temperatures, and for that reason it may be desirable in some
embodiments to apply heat to the applied reaction mixture.
Therefore, a wide range of curing temperatures can be used, such
as, for example, a temperature from 0 to 180.degree. C. A more
typical range is from 4 to 120.degree. C., and a preferred range is
10 to 80.degree. C. This can be done, for example, by (a) heating
one or more of the starting materials prior to mixing it with the
others to form the reaction mixture and/or (b) heating the reaction
mixture after it has been formed by combining the raw
materials.
[0064] Multi-pane glass assemblies made in accordance with the
invention are useful as insulating glass units, as solar modules,
and the like.
[0065] The following examples are provided to illustrate the
invention, but not limit the scope thereof. All parts and
percentages are by weight unless otherwise indicated.
EXAMPLES 1-4
[0066] Example 1 is prepared as follows: A polyol blend is prepared
by mixing 50 parts of a 2000 molecular weight difunctional
poly(1,2-butylene oxide) homopolymer, and 50 parts a 3000 molecular
weight nominally trifunctional poly(1,2-propylene oxide)
homopolymer. To this blend are added 4.5 parts 1,4-butanediol and
about 0.04 parts of a tin catalyst. This blend is mixed with a 143
isocyanate equivalent weight "liquid" MDI product at an isocyanate
index of 1.02 to form a reaction mixture. The resulting cured
elastomer contains 25.2% hard segment. The reaction mixture is
compression molded at 50.degree. C. for 30 minutes under an applied
pressure of 20,000 psi (about 140 MPa) for 30 minutes. Tensile
strength and elongation are measured according to ASTM 1708, and
are as reported in Table 1 below. Results are as indicated in Table
1.
[0067] Examples 2-6 are made in the same manner, except in each
case the 1,4-butanediol is replaced with another chain extender, as
indicated in Table 1. The amount of chain extender and the hard
segment content of the elastomers are as indicated in Table 1. For
Examples 3-6, the Shore A hardness is measured according to ASTM
D2240.
TABLE-US-00001 TABLE 1 Example Chain Extender, Hard Segment Tensile
Strength, Shore A No. amount (parts) Content, % MPa (psi)
Elongation, % Hardness 1 1,4-butanediol, 4.5 25.2 4.07 (590) 324 ND
2 2,2,4-trimethyl pentane-1,3-diol, 6.5 25.5 1.72 (250) 485 ND 3
2-ethyl hexane diol, 6.5 25.5 1.71 (248) 505 30 4 1,2-propane diol,
4 25.4 2.65 (384) 538 35 5 1,3-propane diol, 4 25.4 1.74 (252) 539
31 6 N,N-bis(2-hydroxylpropyl)aniline, 8 25.2 340 (234) 450 40
[0068] When used to seal the edge of a multi-pane glass assembly,
each of Examples 1 through 6 demonstrates excellent adhesion to the
glass and spacer, and forms a high quality seal.
EXAMPLES 7-11
[0069] Example 7 is prepared by mixing 70 parts of a 2000 molecular
weight difunctional poly(1,2-butylene oxide) homopolymer with 30
parts castor oil. To this blend are added 1.5 parts 1,4-butanediol
and 0.04 parts of a tin catalyst. The amount of 1,4-butanediol is
selected so that the resulting cured elastomer contains 25% hard
segment when cured at a 1.1 isocyanate index. This mixture is then
combined with a 143 isocyanate equivalent weight "liquid" MDI
product at an isocyanate index of 1.1 to form a reaction mixture,
which is cured as described with respect to Examples 1-6. Tensile
strength, elongation and Shore A hardness are measured as before,
with results as are indicated in Table 2 below.
[0070] Samples of the cured films are cut into dog-bones for
evaluating the effect of water immersion on mechanical properties.
The initial weight (W.sub.0) of the films is determined. The film
is in each case then immersed for 24 hours in DI water maintained
at 25.degree. C. or in boiling water for 1 hour. After the
specified time, the film is then dried with a tissue to remove
surface water and weighed to obtain weight W.sub.1. The water
absorption is calculated using equation:
Water uptake=(W.sub.1-W.sub.0)/W.sub.0).times.100%
[0071] Examples 8-11 are prepared and tested in the same manner,
except the ratio of poly(1,2-butylene oxide) homopolymer and castor
oil is varied as indicated in Table 2.
TABLE-US-00002 TABLE 2 Mechanical Properties Poly(BO)/ Water
Tensile Ex. Castor Oil uptake, Strength, Elongation, Shore A No.
Ratio.sup.1 wt-% MPa (psi) % hardness 7 70/30 0.69 2.41 (350) 295
55 8 75/25 0.72 2.05 (297) 294 50 9 80/20 0.79 1.86 (270) 236 50 10
85/15 0.81 1.92 (279) 450 39 11 90/10 0.92 1.57 (227) 445 33
.sup.1The weight ratio of the poly(butylene oxide) diol and the
castor oil in the formulation.
[0072] When used to seal the edge of a multi-pane glass assembly,
each of Examples 7 through 11 demonstrates excellent adhesion to
the glass and spacer, and forms a high quality seal.
EXAMPLE 12
[0073] A sealant composition is made and cured in the general
manner described in the previous examples. The formulation is 85
parts of a 2000 molecular weight difunctional poly(1,2-butylene
oxide) homopolymer, 15 parts castor oil, 1.5 parts of 1,4
butanediol, 0.05 parts of tin catalyst and 26.3 parts of the 143
equivalent weight "liquid" MDI. The resulting elastomer is cured at
50.degree. C. for three days. Its tensile strength is about 200 MPa
(290 psi) and its elongation is about 440. The water uptake is 0.8%
by weight.
[0074] Moisture Vapor Transmission Rates (MVTR) are analyzed on a
MOCON Permatran-W 3/33 Water vapor permeability instrument.
Standards that apply to the instrument include ASTM F-1249, TAPPI
T557 and JIS K-7129. The moisture vapor transmission rate is 1.6
g/(100 in.sup.2/day) (0.103 g/m.sup.2/day).
[0075] Oxygen Transmission Rates (OTR) are analyzed on a MOCON
Oxtran 2/21 instrument. Standards that apply to the instrument
include ASTM D-3985, ASTM F-1927, DIN 53380, JIS K-7126 and ISO CD
15105-2. The oxygen transmission rate is 80 mL/(100 in.sup.2/day)
(5.16 mL/m.sup.2/day).
[0076] The moisture vapor transmission and oxygen transmission
values indicate the suitability of this elastomer for use as a
secondary sealant in an IGU.
EXAMPLES 13-18
[0077] Example 13 is prepared by mixing 85 parts of a 2000
molecular weight difunctional poly(1,2-butylene oxide) homopolymer
with 15 parts of castor oil. To this blend are added 1.5 parts of
1,4-butanediol and 0.04 parts of a tin catalyst. 50 Parts of
trimethyl pentanyl diisobutyrate (TXIB plasticizer from Eastman
Chemicals) are added, as are 268.5 parts of calcium carbonate
particulates, 2 parts of a silane adhesion promoter, 2 parts of an
antioxidant and 5 parts by weight of a color paste. The resulting
mixture is then combined with 24.4 parts of a 143 isocyanate
equivalent weight "liquid" MDI product to form a reaction mixture,
which is cured as described with respect to Examples 1-6. Tensile
strength, elongation and Shore A hardness are measured as before,
with results as are indicated in Table 3 below.
[0078] Examples 14-18 are prepared and tested in the same manner,
except the amount of plasticizer is varied as indicated in Table
3.
TABLE-US-00003 TABLE 3 Mechanical Properties Plasticizer Tensile
Ex. parts by Strength, Elongation, Shore A No. weight MPa (psi) %
hardness 13 50 4.00 (580) 168 65 14 45 2.85 (414) 248 62 15 40 2.81
(408) 308 60 16 30 2.93 (425) 328 60 17 20 2.00 (291) 260 38 18 10
1.87 (271) 277 35
[0079] When used to seal the edge of a multi-pane glass assembly,
each of Examples 13 through 18 demonstrates excellent adhesion to
the glass and spacer, and forms a high quality seal.
[0080] All of these formulations have viscosities low enough to
process easily even though many of them, especially Example 18,
contain only a small amount of plasticizer and have high filler
levels.
* * * * *